Catheter having improved bonding region

ABSTRACT

A method of making a catheter having a flexible outer tube and a lubricious inner tube bonded to the flexible outer tube. The catheter is formed of a distal outer tube formed of a first, flexible material, an inner tube having a lubricious inside wall surface formed of a second, lubricious material, and an outer tube wall surface compatible with heat bonding the inner tube outside wall surface to the outer tube wall surfaces. A preferred flexible material is polyether block amide (PEBA) and a preferred lubricious material is polyethylene.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 12/907,593 filed Oct. 19, 2010, now U.S. Pat. No. 8,292,874, whichis a continuation application of U.S. application Ser. No. 11/379,534filed Apr. 20, 2006, now U.S. Pat. No. 7,815,625, which is acontinuation application of U.S. application Ser. No. 09/178,126 filedOct. 23, 1998, now abandoned.

FIELD OF THE INVENTION

The present invention relates generally to medical devices. Morespecifically, the present invention relates to angioplasty catheters. Inparticular, the present invention includes angioplasty catheters havingdistal, short, lubricious inner guide wire tubes bonded within flexibleouter tubes.

BACKGROUND OF THE INVENTION

Angioplasty procedures have gained wide acceptance in recent years asefficient and effective methods for treating types of vascular disease.In particular, angioplasty is widely used for opening stenoses in thecoronary arteries and is used for treating stenoses in other vascularregions.

One widely used form of angioplasty makes use of a dilatation catheterwhich has a inflatable balloon at the distal end and a guide wire lumenwithin at least a portion of the catheter shaft. Typically, a guide wireis inserted through the vascular system to a position near the stenoses,leaving a proximal portion of the guide wire extending from the patient.The proximal guide wire portion is threaded through the dilatationcatheter guide wire lumen, and the dilatation catheter is advancedthrough the vascular system over the guide wire to a position near thestenoses. The treating physician manipulates the dilatation catheteruntil the balloon is positioned across the stenoses. The balloon is theninflated by supplying fluid under pressure through an inflation lumen inthe catheter to the balloon. The inflation of the balloon widens thevessel lumen through the stenosed area by pressing the inflating balloonwall against the lesion inside wall.

One class of dilatation catheters, termed “Single Operator Exchange”(SOE) or “Rapid Exchange” catheters, have only a short, distal guidewire lumen, to allow for easy removal and replacement of catheters whilerequiring only a short length of guide wire extending proximally from apatient. These catheters include a distal portion having multipledesired attributes. The catheter distal portion preferably has a smallprofile or cross-sectional area and is very flexible, to allow fortraversing narrow and tortuous vessel paths. The distal portion may alsorequire a guide wire tube having a lumen, which increases the profile.The guide wire lumen preferably has a lubricious inside wall to easemovement of the catheter over the guide wire.

Many current SOE catheters have outer polyethylene tubes and innerpolyethylene guide wire tubes inserted therein. An orifice can becreated in the side of the outer tube wall and the inner tube insertedthrough the orifice. The inner tube is inserted so as to extendlongitudinally through the lumen of the outer tube. On one side of theinner tube, distal of the orifice, the outside surface of the inner tuberuns close to the inside surface of the outer tube. On the oppositedirection, proximal of the orifice, the outside surface of the innertube runs along the outside surface of the outer tube, in a crimped orbuckled hollow surface region. The close proximity of the tube surfacessuggests bonding using adhesive or heat bonding. Heat bonding ispreferred to adhesive bonding.

Polyether block amide (PEBA) tubes have greater flexibility thanpolyethylene tubes, and it would be desirable to use PEBA tubes for theouter tubes. It is very desirable to have the inner and outer tubesformed of mutually compatible materials to enable heat bonding. Use ofPEBA for guide wire inner tubes would provide such heat bondingcompatibility. PEBA is generally less lubricious than polyethylene,however, making polyethylene a more desirable material for forming theinner tube. Lubricity is important for providing a low friction innersurface for accepting a guide wire. What would be desirable is acatheter allowing for use of a more flexible outer tube while retainingthe benefits of a more lubricious inner tube while allowing high-qualityheat bonding between the two tubes.

SUMMARY OF THE INVENTION

The present invention includes catheters having a first tube formedprimarily of a first material bonded to a second tube having an insidesurface formed primarily of a second material, where the first andsecond materials may be unsuited for high quality direct bonding. Onecatheter has a first tube formed of a flexible material such aspolyether block amide and a second, tri-layer tube having a lubriciousinside layer such as polyethylene, a flexible outside layer formed ofthe same material as the first tube outside surface, and an intermediatetie-layer suitable for joining the lubricious and flexible layers. In apreferred embodiment, the first tube has an orifice through a wall andthe second tube is inserted through the wall and distally disposedwithin the first, outer tube. In a preferred embodiment, the first tubefunctions as a distal catheter shaft and the second tube functions as ashort, distal guide wire tube disposed within, and bonded to, the firsttube.

Catheters incorporating the invention include single operator exchange(SOE) angioplasty balloon catheters having a proximal shaft, a distalshaft including a first tube coupled to the proximal shaft, distallydisposed inflatable balloon, and an orifice through the wall of thefirst tube disposed proximal of the balloon. In these catheters, asecond guide wire tube can be inserted through the orifice and disposeddistally of the orifice, commonly extending through the balloon regionand ending in a distal guide wire port near the distal end of thecatheter. The SOE catheters preferably have a lubricious materialforming the inside layer of the inner tube and a flexible materialforming most of the outer tube. A preferred lubricious material ispolyethylene (PE) and a preferred flexible material is polyether blockamide (PEBA).

One SOE catheter has a polyethylene inner tube disposed within atri-layer outer tube having an inside PE layer, an outer PEBA layer, anda PLEXAR™ tie-layer disposed therebetween. The outer tube inside surfacecan be bonded to the inner tube outside surface. Another SOE catheterhas a PE inner tube disposed within an interrupted tri-layer outer tubehaving a proximal PE portion, a distal PEBA portion, and a tie-layerinterrupting the PE and PEBA portions. The inner tube outside surfacecan be bonded to the outer tube PE portion inside and outside surfaces.Another SOE catheter has a PEBA outer tube and an interrupted tri-layerinner tube disposed therein having a proximal PEBA portion, a distal PEportion, and a tie-layer disposed therebetween. The inner tube PEBAportion can be bonded to the outer tube PEBA inside and outsidesurfaces. Another SOE catheter includes a PEBA outer tube and a PE innertube having a proximal tri-layer portion having a tie-layer disposedover the inside PE layer and a PEBA layer disposed over the tie-layer.The inner tube proximal portion outside PEBA surface can be bonded tothe outer tube PEBA inside and outside surfaces.

Yet another SOE catheter includes a PEBA outer tube and a tri-layerinner tube having a PE inside layer, a PEBA outside layer, and atie-layer disposed therebetween. The inner tube outside PEBA surface canbe bonded to the outer tube PEBA inside and outside surfaces. In stillanother SOE catheter, an outer PEBA tube has a bi-layer inner tubedisposed within including an inside high density PE (HDPE) layer and aPLEXAR™ tie-layer disposed over the HDPE inside layer. The inner tubeoutside tie-layer can be bonded to the outer tube PEBA inside surface.In one more embodiment, an SOE catheter includes a PEBA outer tube andan inner tube having a proximal PEBA portion butt-welded to a distaltri-layer portion having a PE inside layer, a PEBA outside layer, and atie-layer disposed therebetween.

The present invention can provide catheters having the advantages of alubricious guide wire tube, a flexible catheter shaft, and a secure bondbetween the lubricious material and the flexible material. Cathetersaccording to the present invention can provide the advantages of bothmaterials as well as providing the advantages of heat bonding the twomaterials.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal, cross-sectional view of a balloon angioplastycatheter including an inner guide wire tube inserted through an orificein an outer tube and disposed within the outer tube;

FIG. 2 is a fragmentary, longitudinal cross-sectional view of a distalportion of the catheter of FIG. 1, illustrating an inner tube extendingthrough an orifice in an outer tube;

FIG. 3 is a transverse, cross-sectional view taken through 3-3 in FIG.1, illustrating an outer tube, an inner tube, and a core wire;

FIG. 4 is a longitudinal, cross-sectional view of an inner guide wiretube inserted within and bonded to a tri-layer outer tube, wherein theouter tube has an inside surface compatible with the outside surface ofthe inner tube;

FIG. 5 is a longitudinal, cross-sectional view of a tri-layer innerguide wire tube inserted within and bonded to an outer tube, wherein theinner tube has an outside surface compatible with the inside surface ofthe outer tube;

FIG. 6 is a longitudinal, cross-sectional view of an inner guide wiretube inserted within and bonded to an interrupted tri-layer outer tube,wherein the outer tube has a proximal portion inside surface compatiblewith the outside surface of the inner tube, an intermediate portiontie-layer, and a distal portion having different properties than theproximal portion;

FIG. 7 is a longitudinal, cross-sectional view of an interruptedtri-layer inner guide wire tube inserted within and bonded to an outertube, wherein the inner tube has a proximal portion outside surfacecompatible with the inside surface of the outer tube, an intermediateportion tie-layer, and a distal portion having different properties thanthe proximal portion;

FIG. 8 is a longitudinal, cross-sectional view of an inner guide wiretube inserted within and bonded to an outer tube, wherein the inner tubehas a short, proximal tri-layer portion having an outside surfacecompatible with the inside surface of the outer tube and a distalportion having an outside surface corresponding to the inside layer ofthe tri-layer portion;

FIG. 9 a longitudinal, cross-sectional view of a bi-layer inner guidewire tube inserted within and bonded to an outer tube, wherein the innertube has an outside tie-layer compatible with the inside surface of theouter tube; and

FIG. 10 is a longitudinal, cross-sectional view of an inner guide wiretube inserted within and bonded to an outer tube, wherein the inner tubehas a proximal portion having an outside surface compatible with theinside surface of the outer tube and a distal portion having differentproperties than the proximal portion butt-welded to the proximalportion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a balloon angioplasty catheter 20, which demonstratesone catheter incorporating the present invention. Catheter 20 extendsfrom a proximal region 22 through an intermediate region 24 to a distalregion 26. Proximal region 22 includes a manifold 28, a strain relief30, and a proximal shaft 32. Proximal shaft 32 includes a proximalregion 34 having an outer hypotube construction and a distal region 36having a polymeric construction, continuing distally after the hypotubeterminates. The term “hypotube,” as used herein, refers generally to athin walled, high-strength metallic tube having a lumen within. Thehypotube is preferably a stainless steel hypodermic tube. In oneembodiment, a core wire or stiffener 37 can be included in proximalregion 22 and intermediate region 24 to provide additional stiffness andpushability to catheter 20 to enable pushing the catheter distal portioninto distant body regions without buckling.

A distal shaft 42 includes an outer tube 46 and an orifice 48 throughthe outer wall of outer tube 46 and a lumen 47 within. A balloon 50 isdisposed distally on distal shaft 42, having an envelope 52, a proximalwaist 54, and a distal waist 56. An inner tube 58 is inserted into outertube 46 and lumen 47 through orifice 48. Inner tube 58 serves as adistal guide wire tube in catheter 20. The relatively short length ofinner tube 58 allows the single operator or rapid exchange of catheter20 over a guide wire. Inner tube 58 includes a proximal orifice 70, aproximal end 71, a proximal portion 60, an intermediate portion 62, adistal portion 64, a distal end 66, a distal orifice 68, and a guidewire lumen 59 within. In use, a guide wire (not requiring illustration)can be threaded through proximal orifice 70, through lumen 59, exitingthrough distal orifice 68. Inner tube 58 is preferably substantiallycongruent within outer tube 46 for much of the length of inner tube 58.The entry of inner tube 58 through orifice 48 can include a buckled orconcave region 72, also illustrated in FIG. 2 at 806. In this buckledregion, inner tube 58 can lie atop outer tube 46 proximal of entryorifice 48. The entry of inner tube 58 into outer tube 46 preferablyincludes bonding or affixing of the tubes to secure inner tube 58 inplace. This bonding preferably includes bonding in the region proximateorifice 48 and can include bonding both proximal and distal of orifice48.

Referring now to FIG. 2, the region proximate the entry of the innertube into the outer tube is illustrated in greater detail. Theembodiments illustrated in FIGS. 4-10 can share many of the structuralfeatures of the embodiment of FIG. 2, while having different tubeconstruction and bonding. FIG. 2 illustrates a catheter distal region800 including an outer tube 802 having an orifice 804 therein and aninner guide wire tube 805 inserted distally though orifice 804. Anorifice such as orifice 804 can be formed by making a slit or removingmaterial and creating a hole in the outer tube wall. The orifice canserve to admit the inner tube into the outer tube. Inner tube 805includes a proximal end 810, a proximal portion 812, a proximal orifice808, and a guide wire lumen 816 through inner tube 805. Inner tube 805lies in a buckled or concave region 806 in outer tube 802 proximal ofwhere inner tube proximal portion 812 extends into outer tube 802. Inone embodiment, the bonding region lies generally proximate orifice 804,which can be used for bonding of inner tube 805 to outer tube 802. Innertube 805 includes an inner tube wall 818, an inside wall surface 822,and an outside wall surface 820. Inner tube 805 includes a distalportion 814, which lies distal of proximal portion 812. Outer tube 802includes a proximal portion 830, a tube wall 831, an outside wallsurface 832, and an inside surface 840.

In one embodiment, inner tube wall 818 is formed of a lubriciousmaterial to provide a lubricious inside surface 822 offering lessresistance when advancing the catheter over a guide wire. In thisembodiment, outer tube wall 831 is formed of the same or compatiblelubricious material as inner tube 805. This allows bonding between innerand outer tubes as indicated, for example, at region 850. In someembodiments, bonding occurs distal of orifice 804 and near orifice 804.In other embodiments, the bonding occurs further distal of orifice 804.In other embodiments, bonding occurs proximal of orifice 804 asindicated, for example, by region 851. Any suitable location for bondinginner to outer tubes is within the scope of the invention.

Referring now to FIG. 3, a transverse cross section taken through 3-3 inFIG. 1 is further illustrated. Outer tube 46 has been heat bonded toinner tube 58, resulting in an area of melted polymer 47 between theinner and outer tubes. Guide wire lumen 59 is illustrated, together withcore wire 37 and an inflation lumen 61. In one method, after the innertube is positioned within the outer tube, mandrels corresponding to theguide wire and inflation lumens are positioned within the inner andouter tubes respectively. The tubular assembly is heated, resulting in are-melt or re-flow of polymeric material and heat bonding.

Referring now to FIG. 4, a catheter distal region 100 is illustrated,including an outer tube 102 having an orifice 104 therein, and an innerguide wire tube 105 inserted distally though orifice 104. Inner tube 105includes a proximal portion 112 and a guide wire lumen 116 through innertube 105. Inner tube 105 lies in a buckled or concave region 106 inouter tube 102 proximal of where inner tube proximal portion 112 extendsinto outer tube 102. In one embodiment, the bonding region liesgenerally proximate orifice 104, which can be used for bonding of innertube 105 to outer tube 102. Inner tube 105 includes an inner tube wall118, an inside wall surface 120, and an outside wall surface 122. Innertube 105 includes a distal portion 114, which lies distal of proximalportion 112. Outer tube 102 includes a proximal portion 130, a tube wall131, an outside wall surface 132, an outside layer 134, an intermediatetie-layer 136, an inside layer 138, and an inside surface 140.

In one embodiment, inner tube wall 118 is formed of a lubriciousmaterial to provide a lubricious inside surface 120 offering lessresistance when advancing the catheter over a guide wire. In thisembodiment, outer tube wall inside surface 140 is formed of the same orcompatible lubricious material as inner tube 105. This allows bondingbetween inner and outer tubes as indicated in region 150. As illustratedin FIG. 4, inner tube 105 and outer tube inner layer 138 are formed ofthe same material. After heat bonding, the two layers can melt and flowtogether as indicated by the dashed line between layer 138 and innertube wall 105. In the example illustrated, bonding only occurs distal oforifice 104 and near orifice 104. In other embodiments, the bondingoccurs further distal of orifice 104. Any suitable location for bondinginner to outer tubes is within the scope of the invention. Outer tube102 has an outside layer 134 formed of a flexible material differentfrom the lubricious material forming inner tube 105. Disposed betweenoutside layer 134 and inside layer 138 is tie-layer 136.

Tie-layer 136, as used herein, refers to a layer which enables orenhances the bonding of the two materials such as the outside and insidelayers to one another. The outer tube outside and inside layers canprovide different properties desirable for the catheter. In particular,the outside layer can contribute much of the structural properties ofthe outer tube, while the inside layer can contribute an inside surfacethat is bond compatible with the outside surface of the inner tube. Thetie-layer is preferably a layer of polymer that is bond compatible withboth inside and outside layers. The tie-layer can in turn be formed ofmore than one layer, but a single layer is preferred to provide a thintube wall. In some embodiments, the tie-layer enables two materials tobond to one another where such bonding would not occur in the absence ofthe tie-layer. In other embodiments, the tie-layer enhances bonding,improving the bond strength over that which would otherwise occur. Atie-layer can greatly improve the quality of bonding.

In one embodiment, inner tube 105 is formed of polyethylene, outer tubeinside layer 138 is also formed of polyethylene, and outer tube outsidelayer 134 is formed of a polyether block amide (PEBA) such as PEBAX™. Atie-layer suited for bonding polyethylene and PEBA together such asPLEXAR™ or KRATON™ is used for tie-layer 136 in one embodiment. In someembodiments, a surface treatment can be used to form the tie-layer. Inan embodiment having a polyethylene inner tube, the polyethyleneprovides a lubricious inside tube surface for a guide wire to slidewithin. In an embodiment having a PEBA outer tube outer layer, the PEBAprovides a strong, yet flexible material, having superior flexibility topolyethylene in most catheter applications. The flexibility is ofimportance in the distal catheter region, which may be required totraverse tortuous secondary and tertiary coronary vessels.

The polyethylene inner tube provides the advantages of a lubriciousinner surface, while the tri-layer outer tube provides flexibilityimparted by the PEBA outside layer. The polyethylene outer tube insidelayer provides a layer compatible for heat bonding with the polyethyleneinner tube outside surface. The outer tube tie-layer provides a meansfor joining the outer tube polyethylene and PEBA layers. Catheter distalregion 100 thus has the advantages of a lubricious guide wire lumen andthe advantages of a distal catheter outer tube formed of a flexiblematerial.

Referring now to FIG. 5, another embodiment of the invention isillustrated in a catheter distal region 200 including an inner tube 205disposed within an orifice 204 in an outer tube 202. Outer tube 202includes a proximal portion 230, a tube wall 231, an outside surface232, and an inside surface 240. Outer tube 202 and tube wall 231 areformed of a first material extending from outside surface 232 to insidesurface 240. Inner tube 205 includes a tube wall 218 having an insidesurface 220, an inside layer 221, a tie-layer 225, an outside layer 223,and an outside surface 222. Inner tube inside layer 221 is formed of asecond, lubricious material, and outside layer 223 is preferably formedof the first material or a material bond compatible with the firstmaterial. Tie-layer 225 provides a bond, holding inside layer 221 andoutside layer 223 together. Outer tube inside surface 240 and inner tubeoutside surface 222 are formed of the same first material, allowing forformation of a good heat bond securing the inner tube within the outertube. In the bonding region proximate orifice 204, the inner and outertubes are secured at a distal bonding region 250 disposed distal oforifice 204 and at a proximal bonding region disposed proximal oforifice 204, better visualized by bonding region 851 in FIG. 2, as areother bonding regions disposed proximal of the orifice in figuressimilar to FIG. 5. Outer tube 202 can be bonded to inner tube 205 usingboth outer tube inside surface 240 and outside surface 222. In apreferred embodiment, the first material forming outer tube 202 is PEBA,as is the material forming inner tube outside layer 223, while thesecond material forming inner tube inside layer 221 is polyethylene. Theembodiment illustrated thus can have a lubricious polyethylene insidesurface for the guide wire lumen and a flexible PEBA outer tube.

Referring now to FIG. 6, a catheter distal region 300 having aninterrupted tri-layer outer tube is illustrated. Catheter distal region300 includes an inner tube 305 disposed within an orifice 304 in anouter tube 302. Inner tube 305 includes a wall 318, an inside surface320, and an outside surface 322. Outer tube 302 includes a tube wall 331having an inside surface 340, an outside surface 332, a proximal portion330, a distal portion 342, and an intermediate portion 337 disposedbetween the proximal and distal portions. In a preferred embodiment,intermediate portion 337 includes a tie-layer 336 formed as a shortlayer disposed at an angle relative to the tube wall, such thattie-layer 336 extends over a length indicated at “D1” in FIG. 6.Tie-layer 336, as illustrated, longitudinally separates or interruptsthe proximal and distal portions of the layer. In a preferredembodiment, D1 has a length between about one (1) mm and one hundred(100) mm and a width of about one hundred (100) mm. In one method,tie-layer 336 is formed using a Short and Controlled Transition Section(SCTS) extrusion technique, as described in U.S. Pat. No. 5,533,985,issued to Wang, herein incorporated by reference. In one embodiment,inner tube 305 is formed of polyethylene, and outer tube 302 hasproximal portion 330 formed of polyethylene, tie-layer 336 formed ofPLEXAR™, and distal portion 342 formed of PEBA. In one embodiment, innertube outside surface 322 is bonded to outer tube inside surface 340, asindicated at 350 and by region 851 in FIG. 2 as discussed previously. Inembodiments supporting bonding involving both the inside and outsidesurface of the outer tube, the bonding region can extend both proximaland distal of orifice 304. Bonding can also extend over the sides ofinner tube 305 but is not illustrated in the longitudinal,cross-sectional view of FIG. 6. The embodiment of FIG. 6 thus provides alubricious inner tube for ease of guide wire movement and an outer tubeproximal portion for bonding to the lubricious inner tube, whileproviding a flexible material forming most of the outer tube.

Referring now to FIG. 7, a catheter distal region 400 having aninterrupted tri-layer inner tube is illustrated. Catheter distal region400 includes an outer tube 402 having an inner tube 405 disposed withinan orifice 404 in outer tube 402. Inner tube 405 includes a proximalportion 412, a distal portion 414, and an intermediate portion 413having a length indicated at “D2”. Intermediate portion length D2 ispreferably between about one (1) mm and fifty (50) mm. Intermediateportion 413 includes a tie-layer 436 preferably disposed at an anglerelative to the inner tube wall. In one method, tie-layer 436 is formedusing a Short and Controlled Transition Section (SCTS) extrusiontechnique previously described. Outer tube 402 and inner tube proximalportion 412 are preferably formed of the same flexible material to allowfor improved bonding. Inner tube distal portion 414 is preferably formedof a lubricious material, while tie-layer 436 is preferably formed of amaterial suitable for adhering the flexible and lubricious materialstogether. In one embodiment, the inner tube proximal portion 412 isbonded to outer tube 402, as indicated at 450 and by region 851 in FIG.2. The embodiment illustrated thus provides a lubricious material formost of the length of inner tube 405, while providing a flexiblematerial for outer tube 402. Forming inner tube proximal portion 412 ofa bond compatible or identical material to the material of the outertube allows bonding together of the inner and outer tubes.

Referring now to FIG. 8, a catheter distal region 500 is illustratedhaving an inner tube 505 inserted into an orifice 504 in an outer tube502. Inner tube 505 includes a tube wall 518, a proximal portion 512,and a distal portion 514. In proximal portion 512, inner tube wall 518includes an inner layer 517, which is preferably formed of the samematerial as the entire tube wall at distal portion 514, a tie-layer 536disposed over the tube wall or inner layer 517, and an outside layer 534disposed over the tie-layer. The proximal portion of inner tube 505 thuscan have two added outer layers in the proximal portion. In a preferredembodiment, outer tube 502 is formed of a flexible material and innertube outside layer 534 is formed of the same material, thereby allowingfor bond compatibility between inner and outer tubes. In a preferredembodiment, inner tube wall 518 is primarily formed of a lubriciousmaterial, and tie-layer 536 is formed of a material able to bond to boththe inner lubricious material and the outer flexible material. In theembodiment illustrated, bonding occurs as indicated at 550 and at 851 inFIG. 2. In one embodiment, inner tube proximal portion 512 is formedusing SCTS technology previously described. The portion of inner tubehaving the tie-layer and outside layer can be disposed anywhere on theinner tube where bonding to the outer tube is contemplated. In oneembodiment, multiple short tri-layer portions are disposed over thelength of the inner tube. In this embodiment, the added two layers areadded to an inner tube where needed. The additional two layers over theinner tube preserves the lubricious inner walls of the inner tube whileimproving the bonding compatibility between the inner and outer tubes.In one embodiment, inner tube inside layer 517 and distal portion 514are formed of polyethylene, tie-layer 536 is formed of PLEXAR™, andoutside layer 534 is formed of PEBA. The embodiment provides alubricious lumen wall for guide wire movement and a flexible catheterouter tube.

Referring now to FIG. 9, a catheter distal region 600 is illustratedhaving a two-layer inner tube 605 disposed within an orifice 604 and inan outer tube 602. Inner tube 605 has a tube wall 618 formed of aninside layer 638 and an outside tie-layer 636. Inner tube inside layer638 is preferably formed of a lubricious material and outer tube 602 ispreferably formed of a flexible material different from the materialforming the inner tube inside layer. Bonding between inner and outertubes is indicated at 650, but the bonding location is varied indifferent embodiments. In one embodiment, inside layer 638 is formed ofpolyethylene, tie-layer 636 is formed of PLEXAR™, and outer tube 602 isformed of PEBA. The catheter distal region illustrated in FIG. 9 canhave a lubricious inner tube inside wall for guide wire movement and aflexible outer tube wall.

Referring now to FIG. 10, a catheter distal region 700 having abutt-welded proximal portion is illustrated. Catheter distal region 700includes an inner tube 705 inserted into an orifice 704 and disposedwithin an outer tube 702. Inner tube 705 includes a proximal portion 712butt-welded to a distal portion 714. A weld 713 is indicated between theproximal and distal portions. In one embodiment, outer tube 702 isformed of a flexible material and inner tube proximal portion 712 isformed of the same or a bond compatible material. Inner tube distalportion 714 can include a tri-layer tube wall as illustrated, having aninside layer 738, an outside layer 734, and a tie-layer 736 disposedbetween inside layer 738 and outside layer 734. In a preferredembodiment, outer tube 712 is formed from PEBA, as is inner tubeproximal portion 712. In this embodiment, inner tube distal portion 714includes inside layer 738 formed from polyethylene, where tie-layer 736can be formed from PLEXAR™ and outside layer 734 can be formed fromPEBA. The tri-layer inner tube can provide a lubricious inner surfacefor guide wire movement, while retaining the flexibility contribution ofthe PEBA outer layer. In this embodiment, bonding can occur as indicatedat 750 and 851 in FIG. 2. The embodiment illustrated thus has asubstantial PEBA contribution to flexibility, while providing alubricious guide wire lumen, as most of the inner tube inside layer canbe formed of polyethylene.

FIGS. 4-10 illustrate embodiments of the invention including an orificethrough an outer tube wall and an inner tube inserted through theorifice into the outer tube and disposed distal thereof within the outertube lumen. In another embodiment, a guide wire tube is disposed withinan outer tube without being inserted through a wall. In this embodiment,the outside surface of the inner tube is bonded to the inside surface ofthe outer tube. FIGS. 4-10, and the associated text, illustrate examplesof tube construction and materials compatible with this embodiment. Inyet another embodiment, a first flexible tube has a second tube having alubricious inside surface bonded to the first tube outside surface. Thesecond tube can serve as a guide wire tube. In a variation of thisembodiment, multiple short, external tubes serve as guide wire tubes.FIGS. 5-10, and the associated text, illustrate examples of tubeconstruction and materials compatible with these external guide wiretube embodiments. In these embodiments, the second guide wire tubeoutside surface is bonded to the first tube outside surface.

In a preferred method of making the present invention, the first andsecond tubes are heat bonded together in the bonding region. Otherbonding methods can also be used to take advantage of the compatiblematerials presented for bonding by the present invention. Other bondingmethods believed suitable for use with the present invention includesonic welding and solvent welding.

Numerous characteristics and advantages of the invention covered by thisdocument have been set forth in the foregoing description. It will beunderstood, however, that this disclosure is, in many respects, onlyillustrative. Changes may be made in details, particularly in matters ofshape, size and ordering of steps without exceeding the scope of theinvention. The invention's scope is, of course, defined in the languagein which the appended claims are expressed.

What is claimed is:
 1. A method of making catheter shaft comprising:forming an orifice in a portion of a first tube including an inflationlumen defined by an inside wall surface in fluid contact with a dilationballoon, an outside wall surface, wherein the first tube is formed of afirst material; inserting a second tube through the orifice in the firsttube to extend distally from the orifice inside the inflation lumen, thesecond tube having a proximal end, a distal end, and comprising an innerlayer of lubricious material, an outer layer, and an interveningintermediate layer, the second tube having a length and a lumentherethrough, the inner layer of lubricious material defining an innerwall surface, the outer layer defining an outer wall surface, and abonding region; bonding the outside wall surface of the second tube tothe inside wall surface of the first tube within the bonding region; andbonding the outside wall surface of the second tube to the outside wallsurface of the first tube within the bonding region.
 2. The method ofclaim 1, wherein the outer layer of the second tube comprises a materialthat is re-flow bond-compatible with the first tube first material. 3.The method of claim 1, wherein the outer layer of the second tube isalso formed of the first tube first material.
 4. The method of claim 1,wherein the intervening intermediate layer of the second tube comprisesa material that is re-flow bond-compatible with the lubricious materialof the inner layer of the second tube and with the outer layer of thesecond tube.
 5. The method of claim 1, wherein the second tube comprisesa proximal portion disposed proximally of the orifice formed in thefirst tube and external of the first tube as well as distal portiondisposed distally of the orifice formed in the first tube, within theinflation lumen of the first tube.
 6. The method of claim 1, wherein thefirst tube first material comprises a polyether block amide.
 7. Themethod of claim 1, wherein the outer layer of the second tube comprisesa polyether block amide.
 8. The method of claim 1, wherein the innerlayer of the second tube comprises polyethylene.
 9. The method of claim1, further comprising disposing a stiffener within the first tube. 10.The method of claim 9, wherein the stiffener is disposed within thelumen of the first tube.
 11. The method of claim 9, wherein thestiffener is disposed within the first tube from proximal the proximalend of the second tube to a point distal of the bonding region.